Modern computer systems often use a number of different processors for different computing tasks. For example, in addition to a number of central processing units (CPUs), a modern computer may have a graphics processing unit (GPU) dedicated to certain computational tasks in a graphics pipeline, or a unit dedicated to digital signal processing for audio, all of which are potentially part of an accelerated processing unit (APU) that may contain other units as well. These processors are connected to memory of various types, using buses that may be internal to an APU or externally located on the computer's motherboard.
It is common that a set of applications are created for a computer system such as a video game console or smartphone (the “legacy device”), and when a variant or a more advanced version of the computer system is released (the “new device”) it is desirable for the applications of the legacy device to run flawlessly on the new device without recompilation or any modification that takes into account the properties of the new device. This aspect of the new device, as contained in its hardware architecture, firmware and operating system, is often referred to as “backwards compatibility.”
Backwards compatibility is often achieved through binary compatibility, where the new device is capable of executing programs created for the legacy device. However, when the real time behavior of the category of devices is important to their operation, as is in the case of video game consoles or smartphones, significant differences in the speed of operation of a new device may cause it to fail to be backwards compatible with respect to a legacy device. If the new device is of lower performance than the legacy device, issues that prevent backwards compatibility may arise; this is also true if the new device is of higher performance, or has different performance characteristics when compared to the legacy device.
It is within this context that aspects of the present disclosure arise.